# Questions tagged [f-test]

Any hypothesis test in which the statistic has an F distribution under the null hypothesis.

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### Given two samples from N with known variances how to find probability that one sample's variance is two times larger than the other?

I have two samples with sizes 9 and 11 drawn from two independent normal distributions with variances 21 and 37 respectively. How can I find the probability that the variance of the first sample is ...
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### Comparing two F-test statistics

I have two groups A and B, each of which consists of 5 samples. Each sample is described in a vector of length (>1000) of continuous numeric values (characteristics). I want to test if the sample in ...
19 views

### Extremely High T-Test P-Value but Extremely Low F-Test P-Value

So I'm running a logistic regression on a binomial variable in R and came out with the following model. ...
23 views

### R-squared unbiased when F-test is biased in heteroscedasticity?

If R2 and F-statistic are in functional relationship, is it possible, that in case of heteroscedasticity F-test is biased but R-squared is not?
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### F test fails but t-test does not? [duplicate]

I'm a bit confused about this. I have a model with multiple variables trying to explain the dependent variable. When I use the F test, I don't pass the critical value. But when I seperate the ...
2k views

### If the f-test is insignificant but coefficients are significant, can I use it?

If the linear regression's f-test is insignificant but its coefficients are significant in t-test, can I use this regression and its coefficients? In academic journals, I find people use linear ...
10k views

### F test and t test in linear regression model

F test and t test are performed in regression models. In linear model output in R, we get fitted values and expected values of response variable. Suppose I have height as explanatory variable and ...
111 views

### Testing nested models with clustered errors

I have a simple linear model. $$Y_i = \beta_1X _{1i}+ \beta_2X_{2i}+\beta_3X_{3i}+\epsilon_i$$ I'd like to test if some of my model parameters ($\beta_2$ and $\beta_3$) are jointly different from ...
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### How should one compute the p-values of a two sided F test?

I have been studying this link. However, i can't really figure out how to calculate the p value for a 2 sided F test where the degrees of freedom are different and the F distribution is asymmetric. I ...
151 views

### What is the point in reporting the z statistic of a z-test?

In my field some authors report the z statistic of a z-test in a generalised linear model and others do not. Does reporting the z statistic serve any purpose if the p value of a z-test or of a post-...
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### Comparison of variance between two samples with unequal sample size

The primary goal of my analysis is to compare the variability in the response variable, Blood Pressure, between sample1 and sample2. The secondary goal is to test for a difference in means. I do not ...
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### Can I mix and match F-test and T-test code when I implement a program for some statistical calculations?

I was told to rewrite an old java program that performs some statistical calculations. I was able to solve most of the problems until I ran into this one: The program compares two sets of data over ...
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### Test the difference between average value of 2 random variables

I am doing an exercise on marketing analysis to determine the strategy that a brand should follow based on historical weekly data collected from supermarkets that sell the brand (let say brand1) and 4 ...
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### Why is it possible to get insignificant F statistic (p>0.1) but significant regressor t-tests (p<0.1)? [duplicate]

My results show significant t-tests but an insignificant F-test. Is this possible or are my calculations wrong?